Mechanisms of Douglas-fir resistance to western spruce budworm defoliation: bud burst phenology, photosynthetic compensation and growth rate.
Tree Physiol
; 21(16): 1159-69, 2001 Oct.
Article
em En
| MEDLINE
| ID: mdl-11600338
ABSTRACT
We compared growth rates among mature interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees showing resistance or susceptibility to defoliation caused by western spruce budworm (Choristoneura occidentalis Freeman), and among clones and half-sib seedling progeny of these trees in a greenhouse. We also investigated bud burst phenology and photosynthetic responses of clones to budworm defoliation in greenhouse experiments. Resistant mature trees had a higher radial growth rate than susceptible trees, especially during periods of budworm defoliation. Clones from resistant trees grew larger crowns than clones from susceptible trees, whereas stem base diameter at the ground line and height did not differ. Half-sib seedling progeny from resistant trees had larger stem diameter, height, and total biomass than progeny from susceptible trees. Mean 5-year radial growth increment of mature trees was more strongly correlated with growth of seedlings than with growth of clones. Clones from resistant trees had later bud burst than clones from susceptible trees, and budworm defoliation of clones depended on the degree of synchrony between bud burst phenology and budworm larval feeding. Clones of resistant and susceptible mature trees showed similar responses of net photosynthetic rate to 2 years of budworm defoliation. We conclude that phenotypic differences in crown condition of Douglas-fir trees following western spruce budworm defoliation are influenced by tree genotype and that high growth rate and late bud burst phenology promote tree resistance to budworm defoliation.
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Base de dados:
MEDLINE
Assunto principal:
Árvores
/
Pseudotsuga
/
Mariposas
Limite:
Animals
Idioma:
En
Revista:
Tree Physiol
Assunto da revista:
BOTANICA
/
FISIOLOGIA
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Estados Unidos